The present invention relates, in a first aspect thereof, to a method for automatically bending spacer elements for insulating glass panes—double glazings.
In a second aspect thereof, the present invention relates to an automatic bending machine for carrying out the inventive method.
As is known, the first profile bending machines were introduced into the market about twenty years ago, both for meeting an increased demand of insulating glass panes or glazings, with double or triple glass sheets, and for improving and enhancing the assembling properties of the insulating glass panes, as well as for simplifying the operating personnel work while increasing the throughput.
Thus, from a technical standpoint, the insulating glass pane frames made in a profile bending machine, that is with their four corners bent instead of cut, have constituted a substantial improvement, since a bent angle or corner greatly improves the insulating capability of the inner double or triple glass sheet glazing, and since it prevents breaking regions from being generated in the frame.
In fact, the bent frames have four bent corners and a linear connector closing the open side.
At the glazing corners, which are the points more susceptible to leakages, the bent frame is less subjected to losses or leakages compared to a frame whose four corners or angles are closed by angular joint elements.
Prior profile bending machines carry out the bending process of the insulating pane inner spacer profiles or elements, which spacer profiles are generally made and sold as profile bars or rods having a length of five or six meters with a substantially rectangular cross section and two radiused beveled portions at the bottom part thereof, with a width which may vary from 6 mm to more than 30 mm, even if the most used widths vary from 8 to 24 mm, and with a height usually from 6.3 to 7 mm.
The above mentioned profile bars or rods comprise different materials, which may be generally classified into three material classes.
The most commonly sold bar-spacer elements, which may be processed in a much more simple and economic manner, are made of an aluminium material.
This type of material is the most diffused one on a worldwide level, even if it does not provide optimum results because of its comparatively small thermal insulating capability.
In the last decade, composite profiles have also been developed, consisting of a part of a stainless steel material and a part of a plastic material, which have progressively become more and more important, particularly on the Italian and European market.
The above profiles are the so-called “Warm Edge” profiles or spacer elements.
They provide an improved thermal insulation, because of their small contents of high thermal conductivity materials.
However, the structure of these materials results in a much more complex bending process.
In fact, even though their inner part is made of a plastic material, therefore it may be easily bent, their outer part is made of a steel material, therefore it has a much larger stiffness.
This fact involves that, in order to bend the outer steel structure, it is necessary to provide a very high bending force applied by the profile bending machine.
On the other hand, the plastic material reacts to the bending operation and tends to return to its starting position.
Moreover, to meet the current regulations, the enlargement of the profile at its bending point, with respect to its straight side, must not exceed 0.3 mm, and this also to be properly used in further processing operating steps.
Finally, it is very difficult to achieve a proper aesthetic quality of the inner bent portion, because of the above mentioned factors, which esthetic quality, on the other hand, is an essential aspect of the finished article of manufacture or frame, since such a finished frame will be visible inside the window or door frame/glazing, therefore it is very important to conceal to the view any defects susceptible to negatively affect the optical properties of the glazing.
The above mentioned factors have as a consequence that, compared to the aluminium profiles, the mentioned “Warm Edge” profiles are much more complex to be processed or machined, and only few prior bending profile machines are actually adapted to provide a proper bending thereof.
To the above it should be also added the fact that, in the last years, on the market have been also introduced some types of bars-profiles which, while being considered as belonging to the “Warm Edge” class, are differentiated from “Warm Edge” profiles both with respect to the thermal conductivity-composition thereof and their very complex machining/bending methods.
The above mentioned bars-profiles are made of composite extruded materials, usually a glass fiber and PVC material, in different rates, with an outer metal film applied on three sides.
This last type of material currently has the most useful operating performance in terms of a lower thermal conductivity, thereby providing the glazing made therefrom with an enhanced value.
However, because of the above mentioned properties, these materials cannot be bent by prior standard profile bending machines, since they must be necessarily subjected to a heating process of the part thereof to be bent, before the bending proper, and to a cooling of the bent section after bending, thereby they were usually considered as unbendable profiles and, for using them to form insulating glass pane frames, they were usually cut to size on the four frame sides, which were then closed by angular joint elements.
This process, even if it could be considered a proper one, involved an increased time requirement for making the related frame, and necessarily a forming of four breakage points at the four corners of the frame.
The working or processing mode of operation of prior profile bending machines, designed for bending only aluminium spacer elements and “Warm Edge” spacer elements which do not require any heating operation before bending, is generally rather similar for all the currently commercially available bending machines, which usually comprise an automated bending and related cutting system.
The bar profiles of a 5 or 6 m length are at first loaded in a bar storing arrangement which comprises a plurality of different operating sections to be used by an operator for loading the profiles to be processed.
More specifically, said profiles are automatically driven into the profile bending machine, where are performed all the process steps required for making the finished frame.
The entraining of the profile, and the measurement of the length necessary to provide the desired frame, are controlled by an encoder and position sensing photocell system.
In particular, after having fed the bar to be processed into the machining section, said bar is brought to a reference or “0” position, or, if necessary, the required “0” point is formed by a cutting operation.
Then, the bar is driven up to provide the desired length of the first side of the frame, which length will correspond to a preset part of the first side of the frame, since said first side will be practically split into two portions, and then it will be closed by a linear connecting arrangement at the end of the frame making operation.
At this time, the machine actuates a plurality of operating functions for performing a bending of the first frame angle or corner.
In particular, the profile is firmly engaged in a locking gripper, to prevent the profile from performing further movements; a forming assembly is arranged on the top part of the profile, for allowing the latter to be bent thereabove, while preventing any deformations of the inner part of the corner.
An automated raising or lifting paddle performs the bending operation by raising or lifting the profile part passed through the bending point in the profile positioning step, thereby providing a first side of the frame.
Upon ending the bending of the first frame angle or corner, the automated raising or lifting paddle will be downward displaced to achieve again the mentioned reference or “0” position; the top forming assembly will return again to its initial standby position, and the locking gripper will be opened to allow the profile to be driven away again.
Then, the bar driving system will be actuated again, to bring the profile or bar to a desired position suitable for bending the second frame angle or corner.
This method of operation will be continued so as to form the complete frame and the overall process will be ended by cutting the profile at the point thereof at which it should be closed by a linear connector to form a finished spacer element to be arranged inside the insulating glazing.
From the above it should be apparent that the bending system is the most important component of the bending machine, and, accordingly, it comprises a plurality of elements, that is a locking gripper; a top forming assembly and an automated bending paddle.
The top forming assembly, in most of prior profile bending machines, consists of a forming element depending on a size and type of the material being processed, therefore it must be replaced for each material changing or switching operation.
Accordingly, the prior bending cycle comprises three operating steps, that is: inserting the top forming assembly inside a gripper; closing the gripper to prevent the bar or profile from being deformed; and raising the bending paddle to bend that part of the profile which has passed through the gripper, and which will constitute a portion of the first side of the frame to be made.
The bending operation is performed with a 90° bending angle, and the profile is bent about the top forming assembly.
Such a bending process is a continuous one.
The measurement size and data related to the frames are set by the machine operator, or derived from optimizing programs and being then transferred to the profile bending machine to allow the latter to automatically perform the overall process.
Prior machines are designed for processing a profile at a time and, after having fully processed each profile, the same machine automatically performs a connection between the bar or profile being machined and the following one arranged in the storing arrangement.
Since the above mentioned “Warm Edge” profiles have structural features very different from aluminium profiles, the profile bending machine must be able to adjust a plurality of settings which are very critical for a proper achievement of the finished frame.
Vice versa, for bending the “Warm Edge” materials to be heated, the above disclosed method must comprise at least a heating step and a system for heating the profile at the section or portion thereof to be bent, as well as a cooling system for cooling the profile after the bending thereof.
Thus, even though bending machines adapted to bend “Warm Edge” profiles which must be heated are commercially available, these prior bending machines do not provide satisfactorily accurate and good aesthetic feature bending results.
In order to process “Warm Edge” materials which must be heated before bending, heating systems for heating the bars-profiles on line on the bending machine have been designed, and the bending machine has been equipped with further specifically designed auxiliary means, for allowing the machine to process the mentioned “Warm Edge” profiles to be heated.
However, a main drawback of the above mentioned prior bending machines, is that an operator cannot process a material which must not be heated and immediately afterwards process one which, on the contrary, must be heated and vice versa.
In fact, between the above two different processing operations, it is necessary to provide a rest period to allow the operator to assemble/disassemble the related proper auxiliary fittings.
Document WO00/69726 discloses a method and a device for forming a corner limited on three sides, from a plate-shaped material with an even surface.
In this prior method and device, the edges of a plate part which lie adjacent the corner are beveled along the main part of their longitudinal extension parallel to the even-surfaced plate part and have a curved outline in the area of the corner which is to be formed, from the beveled lateral edge to the plate of the even-surfaced plate. The curved transition area of the pre-formed blank is then pressed against an abutment tool and brought into contact with at least one zone of the assembly which overlaps the corner area between the lateral size. The corner is then produced by forming the material and is cut in a cutting device.
In this document the corner does not have two converging sides which define a precise 90° angle.
Moreover, this document neither discloses nor suggests to use air heating and cooling means for forming the corner.
Furthermore, this prior method and device are only adapted to process a plate-shaped material with an even surface, and the material is a sheet metal material. Stated otherwise, this prior method and device cannot machine all the materials machined by blowing hot and cold air at the corner region and, moreover, the corner region is not a perfect 90° corner region.
Document U.S. Pat. No. 5,136,871 A discloses a process and an apparatus for bending hollow profile strips into spacer frames for insulating glass panes. In this document, during the bending of a profile strip into a spacer frame for insulating glass panes, the strip is advanced, by a gripper, displaceable in the feeding direction of the hollow profile strip by predetermined distances to such an extent that the location of the profile strip to be bent in a particular case is aligned with respect to a bending abutment. During the bending process, performed by a bending lever, the profile strip is retained by the jaws of a bending head and the gripper moves back into its starting position. After the final advancement of the hollow profile strip, the latter is severed from the introduced profile strip and the final bending step is executed. The hollow profile strip is constantly retained during the production of the spacer frame either by the gripper or by the jaws of the bending head.
This document neither teaches nor suggests to blow heating and cooling air for forming the corner.
Moreover, this document does not provide corners with precise 90° bent angles.
Document U.S. Pat. No. 5,161,401 A discloses an apparatus for making continuously curved hollow profile strips, wherein the radii of curvature and the length of the curved or corner section of the profile strip can be selected extensively arbitrarily.
This latter document does not provide to use heating or cooling air blowing processes and, moreover, the corners of the frame produced thereby have not a precise 90° bending but, as stated, the corner have radii of curvature which can be selected extensively arbitrarily, but not including a precise 90° bent corner arrangement.